Similarly, an identifier used in program source text, such as is meant to stand for a global procedure or data type, could be made to refer to the source text defining the value to be bound to that global at runtime.

Also, some dependencies might not have filenames but are abstract identifiers that might be provided by any number of alternative packages.

You may need to query the/proc/bus/usb filesystem for your available USB identifiers, and you may need to try each identifier to find which one applies to your hardware.